Soot blowing means for air preheaters



A 1937- F. c. AREY ET AL 2,091,

SOOT BLOWING MEANS FOR AIR PREHEATERS Filed May 20, 1936 4 Sheets-Sheet 1 Aug. 31, 1937. F. c. AREY ET AL SOOT BLOWING MEANS FOR AIR PREHEATERS 4 Sheets-Sheet 2 F iled May 20, 1936 lira /z '(07 K44 1,: ah

Aug.: 31, 1937; c, AREY r AL 2,091,622

SOOT BLOWING MEANS FOR AIR PREHEATERS Filed May 20, 1956 4 Sheets-Sheet 3 REVERSING LINE STARTER EMERGENCY CONTROL STOP BUYTON SAFETY SWITCN 777/6727'07"! a 44. a, 14:. flaw k6] W ffwm'og Aug. 31, 1937. Q AREY'ET AL 2,091,622

SOOT BLOWING MEANS FOR AIR PREHEATERS Filed May 20, 1956 4 Sheets-Sheet 4 47 DOUBLE THROW "/LIMIT SWITCH EMERGENCY STOP SWI'? I] E/ 0'0 STARTINGSWITCH My L56 6L9 @i I 135 CLEANING VALVE MAIN VALVE C7 4 try: fl F 4 0 1/ /DOUBLE THROW 26 LIMIT SWITCH MOTOR EMERGENCY STOP SWITCH T REVERSE SWITCH\ Z Mu FORWARD SWITCH /JJ Patented Aug. 31, 1937 UNITED STATES PATENT OFFICE soo'r BLOWING-MEANS FOR AIR PRE- HEATERS Blower Corporation, a corporationof Pennsyl- Vania Application May 20, 1936, Serial No. 80,670

10 Claims.

In Patent No. 1,926,360, granted September 12, 1933, there is disclosed an apparatus for keeping clean the tubes of air preheaters provided with numerous tubes through which the combustion gases from a furnace or furnaces flow. The pres-' ber of transverse rows of tubes. One of the objects of the present invention is to produce means for moving the actual blower element backward and forward and supplying it with steam or other cleaning fluids that will not only be simplerbut shall take up less space than in the construction of the aforesaid patent.

A further object of the present invention is to provide means whereby the blower element may be motor-driven step by step in one direction and be returned in one continuous stroke.

A further object of the present invention is to provide the apparatus with means for automatically reversing its movement at the end of a working stroke and causing it to return to the starting point.

A further object of the present invention is to produce operating means for the blower element which requires only two or three push buttons or the like for fully controlling the same.

A further object of the present inventionis to provide means for setting in operation the motor for driving the blower elementpand at the same time, opening the valve to admit steam or other cleaning fluid.

In carrying out our invention, we connect to the blower element a rack bar and a 'pipe for admitting the cleaning fluid, both'of "which project through the front wall of the casing for the heater, and when the apparatus is idle, lie on the outside of the heater. One of theobjects of the present invention is to insure that these two members be cleaned so as to free them of soot or other foreign substances during eachcycle of operations of the blowing apparatus.

The various features'of novelty 'wherebyour invention is characterized will hereinafter be pointed out with particularity in the claims; but, for a full understanding of'our invention and of its objects and advantages, reference may be had to the following detailed descriptiontaken in connection with the accompanying drawings, wherein:

Figure l is a top. plan view of a:portionof an air preheater having one ofour improved-blowing apparatus-associated therewith; Fig. 2 is a section,-on a larger scale than Fig. 1, on line 2-'- 2 of Figul; '-Fig. 3 is-a view partly in side elevationand partly in section, of so much of the preheater 'as is' showninFig. 1; Fig. 4 is a section on line 4-4-of Fig. 3, but on a larger scale; Fig. 5 is a front view of the preheater; Fig. 6 is'a detail illustrating a modified form of control station; and-Figs. 7 and'8 are diagrams of connections, showing respectively the control systems corresponding to a control station of the type appearing in Fig. 5 andof the type illustrated' in Fig. 6.

Referring to the drawings, l represents a shell or casing containing numerous vertical tubes or small fiues 2 arranged in two sets of rows at right angles to each other; the -transverse rows being comparatively short, and the longitudinal rows being long. It will be understood that the hot gaseous combustion products from afurnace travel upwardly through these tubes or flues, whereas the-air to be preheated flows through the shell or casing in contact with the peripheries of the tubes; there being nothing new in this construction which may be said to represent simply an air preheater of the vertical type.

Our improved apparatus for keeping the tubes or flues clean is arranged above the upper flue sheet 3; and, asinthe aforesaid patent, it comprises a series' of transverse tubular blowing elements l provided with nozzles to discharge steam jets into theopen ends of the tubes; each blowing element having thereon two rows of nozzles 5 and '6. The blowing elements are connected by' longitudinal pipes i and 8, by means of which the whole is tied into a rigid hollow or tubular framework. This framework is suspended from transverse axles Ben the ends of which are suitable wheelsdfl running on'horizontal rails I! which extend from front to rear of the preheater. Above thewheels are other rails l2 whichkeep the wheels from jumping off the rails along which they run.

Steam or other cleaning fluid is supplied to the forward blowing element,"which is the righthand element in -Fig. lgthrough a pipe l4 whichis fixed-at onelend to this blowing element and projectstherefrom out through the front wall of the casing of the air preheater. Surrounding the pipe M is a larger pipe or tubular housing l5 lying wholly outside of the air preheater casing and preferably supportedat one end from the front wall of the latter. The member l5is somewhat longer than the stroke of the tubular blowing frame and is provided at its rear end with a suitable bearing I3 and at its forward end with a stufiing box 16 which permits the pipe 54 to slide lengthwise while preventing steam from escaping past the pipe. The pipe I4 is provided with openings or windows IT at such a point that they will always lie within the surrounding housing l5 regardless of the position of the blowing device. Steam is admitted into the housing l5 through a supply pipe l8 having therein a valve H) which may be operated in any suitable man- 5 ner. Where the entire apparatus is to be auto' matic, it is advisable that the valve be power operated, and we have therefore shown it as being provided with an electrical operating means indicated conventionally at 20.

10 The tubular blowing frame is adapted to be moved lengthwise by power applied to a long rack bar 2| hinged at one end, as indicated at 22, to the middle of the forward blowing element. This rack bar is slidably mounted in a suitable housing 24 projecting forwardly from a transmission housing 25 mounted on the front wall of the preheater casing. The transmission device has a shaft 26 projecting through the forward wall of the housing and there provided with a belt pulley 21. Suitably supported near the transmission device, in front of the preheater, is a motor 28 on the shaft of which is a belt pulley 29 whose axis is parallel to the axis of the pulley 21. A suitable belt 30 passes around the pulleys 21 and 29 so that, when the motor is in operation, the rack bar is driven lengthwise in one direction or the other, depending upon the direction of rotation of the motor.

When the tubular blower frame is moved toward the back of the preheater casing, the inner ends of the pipe l4 and the rack bar 2| enter the casing and move toward the rear, thereby being exposed to the contents of the casing above the fiues. Consequently, more or less soot and other foreign matter will collect on these parts, and we have therefore provided means for cleaning them. In the arrangement shown, as will best be seen in Fig. 4, there is a small pipe 33 arranged on the inner side of the front wall of the preheater casing above the rack bar and the steam supply pipe I4. Branches from the pipe 33 are provided with nozzles arranged in pairs 34, 34 and 35, 35; one pair being adapted to blow a cleaning fluid against opposite sides of the pipe I4 While the other pair performs the same duty with respect to the rack bar. By admitting cleaning fluid under pressure to the pipe 33 while the blowing unit is making a return stroke,'the surfaces of both the pipe l4 and the rack bar are progressively swept clean as they approach near to the front wall of the preheater casing. As can be seen'in Fig. l, the pipe 33 is connected to the main supply pipe through a pipe 36 and a valve 3']. This latter valve may be operated in any suitable way as, for example, through an electromagnetic actuator indicated conventionally at 3B.

As is usual in apparatuses of this kind, the blowing unit is moved step by step, or inched, from its forward position toward the rear to blow a few transverse rows of flues at a time until all of them are cleaned. It is desirable that the operator in charge be apprised at all times of the position of the blowing unit. This can conveniently be accomplished by placing on the outside of the front wall of the preheater a suitable indicator driven from a moving part of the blowing unit. In the arrangement shown, there is fixed to the front wall of the preheater a long vertical tubular casing 39 in which is located a weight 40;

7 this weight being hung from a cable or other flexible member 4! which passes over suitable guide pulleys 42 and is finally attached to the front end of the rack bar 2|. The weight 40 has a finger 44 that projects through a slot 45 that 7 extends throughout substantially the entire length of the casing or housing 39. Beside the slot are arranged suitable graduations 4%, each of which corresponds to a blowing position of the blowing unit. Therefore, as the blowing unit moves back and forth, the finger or pointer 4G indicates the exact position of the unit.

Regardless of whether or not the movements of the blowing unit, after it has once been started, are automatic or semi-automatic, we prefer to provide a limit switch adapted to automatically open the circuit of the motor when the unit reaches its forward position after having completed a blowing operation, and which reverses the motor whenever the unit reaches the rearward limit of its stroke and thereby causes the motor to drive the unit forward again.

The limit switch 47 which appears in Figs. 1, 2 and 5, may be any suitable double-throw switch mounted on the side of the preheater casing in the vicinity of the plane of the tubular blowing unit. The switch shown is of the type having anoperating shaft l which, in this instance, extends through the wall of the preheater casing, provided at its free end with a radial lever 39 by which it may be actuated. The switch is so mounted that normally the lever extends dewnwardly and thus lies in the path of movement of a pair of fingers 59 and El, projecting laterally from the member 8 of the blowing unit. These fingers are spaced apart in the direction from front to rear of the casing a distance equal to the length of a stroke of the blowing unit. When the blowing unit is in its forward position, the finger 5G is engaged with one side of the switch lever or, if it be a snap switch, it will have engaged with one side of the lever until the lever has swung past center; thereby to hold the switch in one of its two positions. The switch remains in that position until the blowing unit has travelled back through a complete stroke, whereupon the finger 5| engages with the switch lever and throws the switch into its other position. When the switch is in this latter position, it causes the motor to be reversed and the blowing unit to start forward on its return stroke.

In the drawings the operating system is one adapted to a three phase motor; power being supplied through three line Wires, A, B and C leading into a switch box 53, through which they are connected to automatic control mechanism housed in a casing 54. The whole is manually controlled through suitable push buttons 55 and 58 or the like. 4

Fig. 7 is a diagram of the electrical system. From this diagram it will be seen that when the switch 51 is closed, the line wires A, B and C are connected directly to the motor terminals D, E and F, respectively, whereas, when the switch 53 is closed, the line wires A, B and C are connected to the terminals E, D and F. Thus, if it be assumed that the switch 5i connects the motor up for forward operation of the motor, whereby the blowing unit is caused to travel from front to rear of the preheater, then the switch 58 may be said to be a reversing switch that will cause the blowing unit to be driven through a return stroke. The switches 51 and 53 are shown as being provided with actuating coils 59 and respectively, by which the switches, normally open, are closed when the coils are energized. Current for energizing the coils 59 and (iii is supplied from the main line through separate circuits controlled by the double-throw limit switch 41. The circuit for the coil 59 includes the push button 55 and a time relay switch 6| of any usual or suitable await-62a:

construction-whereas the-circuit for the coil 60 includes'the push button 56. The push button isnormally open andthe push button: 56 is normally closed; 7

Assuming that the blowing unit is u at the forward limit of its stroke, as illustrated in Figs. 1 and 3,it-wi1l be seen that upon pressing-the push button 55, current will flow fromline wire A through the coil 59 through the time relay switch, through'the push: button switch, through the right-hand contacts: of the limit switch '41 and back to line wire 3'. Thus the coil 59 is energized and the switch: 51 is closed, causing the m'otorto run in the=forward direction- Asloni; as the push button 55 is held closed, the motor will continue to run, but intermittently, under the control of the time .relay switch. By properly setting this switch, the: motor will always run just long enough to move the. blowing unit through a single step, namely through'a distance equal: to the distance between the centers of' one transverse row of flues to be blown, and the. centers of the fiues. of the corresponding row in the next adjacent pair of rows; and the motor will then stopzlong enoughto provide an ample jetting time for cleaning the .fiues over which the nozzles have been brought. When the blowing unit reaches the limit of its rearward movement, the limit. switch 41 .isautomatically thrown into its second working position, namely that in which the left handcontacts irrFig. 7 are engaged with each other whilethe right-hand contacts are separated. When this-occurs, the circuit for the coil 59 is interrupted and the switch 51 is opened. Now, however, the circuit for the actuating coil 69 for the reversingswitch 58'is closed; current flowing from line wire A through coilkfill, through the=closed push button'switch 156, through the left handcontacts of the limit switch 41 and backito line wire'B. It willbeseen that the time relay switch is not-included in this circuit, so thatthe motor runs continuously in the reverse direction-and thereforedrives the blowing unit back to-the starting point in'one single'movement. When the; blowing unitreaches the starting point, namely the position it occupies iniFigs. l and 3, it automatically throws the limit switch 41 back into the position illustrated in Fig. 7; therebybreaking the circuit for energizing the coil 60 of the reversing switchand making the circuit for the 001159 ready to be closed again .by the push button 55 whenever it is desired to have the blowing apparatus perform another cycle.

Since the main steam valve l9 should be opened at the beginning of a working stroke and be closed during the return movement of the blowing unit, the actuating coil 20 for the valve |9 may be energizedwhenever the coil 59 is energized. We. have therefore connected'the coil 20 across the energizing circuit for the coil 59,. in parallel with the latter coil. .However, one terminalof thecoil 20 connectedto the circuit between the push button-55 and the time. relay switch, so that the valve will be held open during the time the motor is stopped through the energi-zation of the coil-59 by the time relay switch. Also, since the supply pipe [4 and the rackbar 2| should be cleaned while the unit is making a return stroke,.the actuating coil .38 for the valve 31 isconnected across the energizing circuit'for thecoil BO of the-reversing switch. Therefore, while the blowing unit is returning to its starting point after the :fl-ucs-have been blown, cleaning fluid will be discharged against the pipe l4 and the rack bar 2|, close to the front wall of the heater casing, so that, astthese members move out through the front-wall of. the casing; their. external surfaces'ar'e clean.

It will thus be seen that all'that the operator need dois to close the. switch. 55- in order Jto start :5

cycle operations, and keep it closed until the blowing. unit has started/back onits return stroke, in order that a cycle.:may be started and then be automatically completed; I-Ie can'stop the motor at any time during a working. stroke by open- 410 ing the switch 55 or allowing it: to open. Similarl y,if it should'be. desired .to stopflthe unit during a=return stroke,..he need only open the normally closed emergency switch 56.

Itit be desired that the operation of the sys- "1*5 tem be not entirely automatic, any of the automatic features may of course be omitted. In some cases, for example,.it.may be desirable that the step by step movement of the blowingunit becontrolled by the operator rather than byan automatic time relay device. In that case there should be two push tbuttons oriswitches corresponding to the push button or switch 55, one for forward-movemenhand the other for reverse,

so as to enable the operator to move theblower unit backward at any time,. particularly if he should causeit to make too long a step. The encased switchapparatus in this instance would appear as shown in Fig. 6;.1the switch box 63 taking the place ofthe box 254 "and containing only 530 the main switches 51 and 58, as there is no longer any time relay switch 6|. In addition to the push buttons 55 and'56,th'ere is the additional push button 64 which, like the. push button'55, 35

are the same as in the automatic system, as is also the circuit for the actuating coil 59 of the switch 51. Paralleling the circuit'for the coil 59', however, isa second circuit containing the actuating coil 60 of the reversing switch and the normally open push button switch 64. What may be termed the regular circuit for energizing the actuating coil of the reversing switch, and which contains the emergency switch 56, is the same as in the automatic. system.. In other words, when the limit: switch is in the position shown in Fig.

8, the motor'may be caused to run in one direc tion or'the other, depending uponwhether the switch 55 or the switch 64-is closed; but, when the limit-switch isshifted into its other position,

the motor canbedriven only in the reverse di- 55 motion and .will'run continuously to drive the blowing'unit through a complete return stroke unless stopped by opening the emergency switch.

In using the semi-automatic control, assuming the blowing unit to be in the. position illustrated in Figs. 1 and 3, theoperator presses the push button 55 and holdsit' down until the pointer on the indicator 39 reaches the first of-the graduations 46 on the indicator. At this time the nozzles are properly located over predetermined 65 transverse rows of fiues. By taking his finger off the push button, the operator causes the motor to stop. The nozzles thus discharge their jets into the underlying flues until the operator again pressesthe pushbutton and starts the blowing unit on its way to its next blowing position. In other words, the operator inches the blowing unit through a working stroke. If-the indicator shows thatthe blowing unit has gone a little'too-far, at any time, the reversing push button may be pressed so as to cause the unit tobe retracted and be properly located. At the end of the working stroke, at which. time the limit switch is thrown into the position opposite that which it occupies in Fig. 8, the motor circuit is automatically closed in a manner to cause the. motor to reverse and drive the blowing unit back to the starting point through a return stroke.

While we have illustrated and described with particularity only a single preferred form of our invention, with a slight modification, we do not desire to be limited to the exact structural details thus illustrated and described; but intend to cover all forms and arrangements which come within the definitions of our invention constituting the app-ended claims.

We claim:

1. In combination, an air preheater casing or the like, a reciprocable blowing unit in the easing, a cleaning fluid supply pipe fixed to said unit and projecting forwardly through the front wall of the casing, a stationary housing on the outside of the casing surrounding the said pipe and having bearings in which the pipe is slidable, means to introduce cleaning fluid into said housing, and said pipe having an opening in the wall thereof at a point within the housing to admit cleaning fiuid thereto, and means to discharge cleaning fluid against the exterior of said pipe in the Vicinity of said front wall of the casing.

2. In combination, an air preheater casing or the like, a reciprocable blowing unit in the casing, a cleaning fluid supply .pipe fixed to said unit and projecting forwardly through the front wall of the casing, a stationary housing on the outside of the casing surrounding the said pipe and having bearings in which the pipe is slidable, means to introduce cleaning fluid into said housing, and said pipe having an opening in the wall thereof at a point within the housing to admit cleaning fluid thereto, an actuating bar arranged parallel to said pipe hingedly connected at its inner end to said unit and projecting through the front wall of the casing, and means on the outside of the casing to move the actuating bar back and forth.

3. In combination, an air preheater casing, or the like, a reciprocable blowing unit in the casing, a cleaning fluid supply pipe fixed to said unit and projecting forwardly through the front wall of the casing, a stationary housing on the outside of the casing surrounding the said pipe and having bearings in which the pipe is slidable, means to introduce cleaning fluid into said housing, and said pipe having an opening in the wall thereof at a point within the housing to admit cleaning fluid thereto, an actuator connected to said unit and projecting through said front wall of the casing, and means to discharge cleaning fiuid against the exterior of the said pipe and the said actuator in the vicinity of said front wall during the movement ,of said unit to- Ward said wall.

4. In combination, a reciprocable blowing unit, a motor for driving the same, and a control system for said motor to permit said unit to move step by step in one direction and automatically to reverse its movement at a predetermined point in its travel and return to the starting point by a continuous movement.

5. In combination, a reciprocable blowing unit, a motor for driving the same, anda control system for said motor automatically .to cause said unit to move step by step in one direction and automatically to reverse its movement at a predetermined point in its travel and return to the starting point by a continuous movement.

6. In combination, a reciprocable blowing unit, an electric motor for driving the same, switch means to cause the motor to be energized for either forward or reverse rotation, a control system for said switch means including a double-throw switch and one or more manually operable switches, and means on said unit to shift said double-throw switch from one of its positions to the other whenever said unit reaches one or the other limit of its reciprocatory movements.

7. In combination, a reciprocable blowing unit, a motor for driving the same, a valve to admit cleaning fluid to said unit, and a control system for said motor and said valve to cause the motor to drive said unit step by step in one direction through a working stroke and automatically to reverse its movement at a predetermined point in its travel and return to the starting point by a continuous movement and to cause said valve to be held open during said working stroke and to be closed during the return stroke.

8. In combination, a reciprocable blowing unit, a motor for driving the same, a valve to admit cleaning fluid to said unit, a control system automatically to cause said unit to move step by step in one direction and automatically to reverse its movement at a predetermined pointin its travel and return to the starting point by a continuous movement, and means associated with said control system automatically to open and close said valve.

9. In combination, a reciprocable blowing unit, an electric motor for driving the same, a valve to admit cleaning fluid to. said unit, an electro-magnetic actuator for said valve, switch means to cause the motor to be energized for either forward or reverse rotation, a control system for said switch means including a double-throw switch and one or more manually operable switches, means associated with said system to cause said actuator to be energized and deenergized, and. means on said unit to shift said double-throw switch from one of its positions to the other whenever said unit reaches one or the other limit of its reciprocatory movements.

10. In combination, an air preheater casing or the like, a reciprocable blowing unit in the casing, a cleaning fiuid supply pipe fixed to said unit and projecting forwardly through the front wall of the casing, a stationary housing on the outside of the casing surrounding the said pipe and having bearings in which the pipe is slidable, means including a valve to introduce cleaning fluid into said housing, and said pipe having an opening in the wall thereof at a point within the housing to admit cleaning fluid thereto, an actuator connected to said unit and projecting through said front wall of the casing, a motor for reciprocating said actuator, means including a valve to discharge cleaning fluid against the exterior of the said pipe and the said actuator in the vicinity of said front wall during the movement of said unit toward said wall, and an electro-magnetic control system for said motor and said valves.

FRED o. AREY. DE LOS E. I-IIBNER, JR. 

